From Late Middle English deducen, borrowed from Latin dēdūcere, the present active infinitive of dēdūcō; from dē- + dūcere (the present active infinitive of dūcō, ultimately from Proto-Indo-European *dewk-).

• (RP) IPA: /dɪˈdjuːs/, /dɪˈdʒuːs/
• (America) IPA: /dɪˈdus/, /də-/, /-ˈdjus/

deduce (deduces, present participle deducing; simple past and past participle deduced)

1. (transitive) To reach (a conclusion) by applying rules of logic or other forms of reasoning to given premises or known facts.

   Synonyms: conclude, infer

   Antonyms: induce

   • 1605, Francis Bacon, “The Second Booke”, in The Twoo Bookes of Francis Bacon. Of the Proficience and Aduancement of Learning, Diuine and Humane, London: […] [Thomas Purfoot and Thomas Creede] for Henrie Tomes, […], →OCLC ↗, folio 110, verso ↗:

     [T]hoſe principles or firſt poſitions, have no diſcordance with that reaſon, which draweth downe and diduceth the inferiour poſitions.

   • 1650, Thomas Browne, “Of the Great Climactericall Year, that is, Sixty Three”, in Pseudodoxia Epidemica: […], 2nd edition, London: […] A[braham] Miller, for Edw[ard] Dod and Nath[aniel] Ekins, […], →OCLC ↗, 4th book, page 187 ↗:

     Laſtly, One way more there may be of miſtake, at that not unuſuall among us, grounded upon a double compute of the year; the one beginning from the 25 of March, the other from the day of our birth unto the ſame again, which is the naturall account. Now hereupon many men frequently miſcaſt their daies; for in their age they diduce the account not from the day of their birth, but the year of our Lord, wherein they were born.

   • 1651, Thomas Hobbes, “Of Counsell”, in Leviathan, or The Matter, Forme, & Power of a Common-wealth Ecclesiasticall and Civill, London: […] [William Wilson] for Andrew Crooke, […], →OCLC ↗, 2nd part (Of Common-wealth), page 132 ↗:

     Counsell, is where a man ſaith, Doe, or Doe not this, and deduceth his reaſons from the benefit that arriveth by it to him to whom he ſaith it. And from this it is evident, that he that giveth Counſell, pretendeth onely (whatſoever he intendeth) the good of him, to whom he giveth it.

   • 1689 (indicated as 1690), [John Locke], “No Innate Principles in the Mind”, in An Essay Concerning Humane Understanding. […], London: […] Eliz[abeth] Holt, for Thomas Basset, […], →OCLC ↗, book I, § 9, page 6 ↗:

     But how then can thoſe Men think the uſe of Reaſon neceſſary to diſcover Principles that are ſupposed innate, when Reaſon (if we may believe them) is nothing elſe, but the Faculty of deducing unknown Truths from Principles or Propoſitions, that are already known?

   • 1816 June – 1831 October 30, Mary W[ollstonecraft] Shelley, “Letter IV. To Mrs. Saville, England.”, in Frankenstein: Or, The Modern Prometheus (Standard Novels; IX), 3rd edition, London: Henry Colburn and Richard Bentley, […], →OCLC ↗, [https://babel.hathitrust.org/cgi/pt?id=emu.000011593191;view=1up;seq=35 page 17]:

     I do not know that the relation of my disasters will be useful to you; yet, when I reflect that you are pursuing the same course, exposing yourself to the same dangers which have rendered me what I am, I imagine that you may deduce an apt moral from my tale; one that may direct you if you succeed in your undertaking, and console you in case of failure.

2. (transitive, uncommon) To examine, explain, or record (something) in an orderly manner.
   • 1625 (first performance), Ben[jamin] Jonson, The Staple of Newes. […], London: […] I[ohn] B[eale] for Robert Allot […], published 1631, →OCLC ↗, Act II, scene ii, page 23 ↗:

     Pye[d-mantle]. […] Sir, I haue drawne / A Pedigree for her Grace, though yet a Nouice / In that ſo noble ſtudy. […] I haue deduc'd her.— […]

   • 1635 June 15 (Gregorian calendar), James Howell, “XXIX. To the Right Honourable Sir Peter Wichts, Lord Ambassador at Constantinople.”, in Epistolæ Ho-Elianæ. Familiar Letters Domestic and Forren. […], 3rd edition, volume I, London: […] Humphrey Mos[e]ley, […], published 1655, →OCLC ↗, section VI, [https://babel.hathitrust.org/cgi/pt?id=mdp.39015049862587;view=1up;seq=270 pages 249–250]:

     It ſeems there is ſome angry Star that hath hung over this Buſineſs of the Palatinate from the beginning of theſe German Wars to this very Day, which will too evidently appear, if one ſhould mark and deduce Matters from their firſt Riſe.

   • a. 1749 (date written), James Thomson, “Spring”, in The Seasons, London: […] A[ndrew] Millar, and sold by Thomas Cadell, […], published 1768, →OCLC ↗, page 23 ↗, lines 573–578:

     Lend me your ſong, ye nightingales! oh pour / The mazy-running ſoul of melody / Into my varied verſe! while I deduce, / From the firſt note the hollow cuckoo ſings, / The ſymphony of Spring, and touch a theme / Unknown to fame, the Paſſion of the groves.

   • 1776, Edward Gibbon, “Reign of Claudius.—Defeat of the Goths.—Victories, Triumph, and Death of Aurelian.”, in The History of the Decline and Fall of the Roman Empire, volume I, London: […] W[illiam] Strahan; and T[homas] Cadell, […], →OCLC ↗, page 296 ↗:

     The general deſign of this work will not permit us minutely to relate the actions of every emperor after he aſcended the throne, much leſs deduce the various fortunes of his private life.

   • 1822, [Walter Scott], chapter I, in Peveril of the Peak. […], volume II, Edinburgh: […] Archibald Constable and Co.; London: Hurst, Robinson, and Co., →OCLC ↗, page 26 ↗:

     If you leave this Isle, and got to the court of England, see what regard there will be paid to the old pedigree that deduces your descent from kings and conquerors.

3. (transitive, archaic) To obtain (something) from some source; to derive.
   • c. 1699 – 1703, Alexander Pope, “The First Book of Statius His Thebais”, in The Works of Mr. Alexander Pope, volume I, London: […] W[illiam] Bowyer, for Bernard Lintot, […], published 1717, →OCLC ↗, pages 303–304 ↗:

     O Goddeſs, ſay, ſhall I deduce my rhimes / From the dire nation in its early times, / Europa’s rape, Agenor’s ſtern decree, / And Cadmus ſearching round the ſpacious ſea?

4. (intransitive, archaic) To be derived or obtained from some source.
   • 1766, William Blackstone, “Of Title by Purchase, and First by Escheat”, in Commentaries on the Laws of England, book II (Of the Rights of Things), Oxford, Oxfordshire: […] Clarendon Press, →OCLC ↗, page 256 ↗:

     [B]y the ſtatute 7 Ann. c. 21 […] it is enacted, that, after the death of the pretender, and his ſons, no attainder for treaſon ſhall extend to the diſinheriting any heir, nor the prejudice of any perſon, other than the offender himſelf: which proviſions have indeed carried the remedy farther, than was required by the hardſhip above complained of; which is only the future obſtruction of deſcents, where the pedigree happens to be deduced through the blood of an attainted anceſtor.

5. (transitive, obsolete) To take away (something); to deduct, to subtract (something).

   to deduce a part from the whole

   • 1632 (first performance), Benjamin Jonson [i.e., Ben Jonson], “The Magnetick Lady: Or, Humors Reconcil'd. A Comedy […]”, in The Workes of Benjamin Jonson. The Second Volume. […] (Second Folio), London: […] Richard Meighen, published 1640, →OCLC ↗, Act II, scene vi, page 26 ↗:

     Pra[ctise]. […] Well, Sir, the Contract / Is with this Gentleman, ten thouſand pound. […] Int[erest]. And what I have furniſh'd him with all o' the by, / To appeare, or ſo: A matter of foure hundred, / To be deduc'd upo' the payment—.

6. (transitive, obsolete, based on the word’s Latin etymon) To lead (something) forth.
   • 1612, [John Selden], “The Third Song. Illustrations.”, in Michael Drayton, edited by [John Selden], Poly-Olbion. Or A Chorographicall Description of Tracts, Riuers, Mountaines, Forests, and Other Parts of this Renowned Isle of Great Britaine, […], London: […] H[umphrey] L[ownes] for Mathew Lownes; I[ohn] Browne; I[ohn] Helme; I[ohn] Busbie, published 1613, →OCLC ↗, page 51 ↗:

     Richard of the Vies will that Penda, K[ing] of Mereland, firſt deduced a colony of Cambridge men hither and cals it Crekelade, as other Kirklade with variety of names: […]

• adduce
• adduction
• conduct
• conduction

• conducive
• deducible
• deduct
• deductible
• deduction
• deductional (rare)
• deductive
• deductively
• deductivism
• deductory (rare)
• duke
• induce
• introduce
• introduction
• reduce
• reduction
• seduce
• subduce
• subduct
• subduction
• transduce
• transduction

• French: déduire
• German: folgern, ableiten, herleiten, deduzieren
• Italian: dedurre
• Portuguese: deduzir
• Russian: де́лать вы́вод
• Spanish: deducir